1. Technical Field
The invention relates to a host migration system and more particularly, to a host migration system with substantially minimized downtime.
2. Background Information
Hosting service providers supply internet services to users who desire to establish their presence on an internet. Internet services include, for example, web hosting services, email services, file transfer protocol (FTP) services, etc. Hosting service providers may be internet service providers that provide an internet access to clients. Alternatively, hosting service providers may focus on more professional hosting services after users have access to the internet. Hosting service providers also may supply domain name registration services as a registrar. Some users may host internet services with their computers at home.
Hosting service providers may have plural servers at their business place. The servers have storage that may be allocated to users who are using hosting services. The servers store user information, emails, communications, and other information as is needed by internet services. In particular, financial and privacy related information such as credit card numbers, passwords of customers, etc. may be stored in the storage of the servers. This type of information needs special protection from any data loss.
Internet users may have access to websites, send emails and transfer files at any time. There are no definite operation hours for internet services. Servers hosting internet services are required to have high uptime. For instance, users may be discouraged from visiting a website having frequent downtime. Hosting services may, however, experience unavoidable downtime. In particular, downtime frequently occurs upon migration of hosting servers. The migration may occur in the following situations. An existing server may require an improved load such as a load distribution regarding disk space, a memory usage, a central processing unit (CPU) usage, etc. The existing server also may be subject to hardware and software upgrade.
The migration also may happen when hosting service providers move in a new data center for business purposes. For example, the new data center may provide hosting service providers with reduced expenses and a better environment for equipment. In other situations, hosting service providers may be out of business so that hosting services are about to be terminated. Further, users may desire to change hosting service providers for various reasons such as low pricing, quality of services, etc.
The migration may cause substantial loss of data including emails, web contents, database contents, etc. In particular, when users of hosting services may engage in e-commerce, any data loss may be disastrous to their business. To minimize any downtime due to migration, hosting service providers may prepare a new server having preset configurations. A great amount of data at an existing server is copied to the new server. Subsequently, Domain Name Server (DNS) setting is changed so that an internet protocol (IP) address of internet services is changed to an IP address of the new server. Then, the existing server may be disabled.
Full propagation of this new IP address may take several hours to several days. The IP address of the existing server may be cached not only at multiple name servers but also at browsers of internet users. It may be difficult to expect when the cached IP address are renewed. During a certain time period, the IP address of the existing server may be still accessed by some internet users during propagation. Users may experience downtime of a hosting service when the existing server is disabled and the new server is activated. Although both the existing server and the new server are concurrently available, some users may provide new information to the existing server. This results in data corruption and data inconsistency. As a result, hosting services experiences unavoidable downtime.